1. Field of the Invention
The present invention is related to a method for manufacturing an automobile AC generator mounted on an engine of an automobile, and also to a method for manufacturing a rectifier applied to the automobile AC generator.
2. Description of the Related Art
FIG. 11 schematically shows a structure of an automobile AC generator.
In FIG. 11, a stator 1 is constructed of a stator core 2 and a stator coil 3 wound on this stator core 2. A rotator 4 is constituted by one pair of pole cores 5 and 6 located opposite to each other; an excitation coil 7 wound between the cores 5 and 6; a rotation shaft 8; and a slip ring 9 fixed on this rotation shaft 8. A front bracket 12 is provided with an intake port 12a and an exhaust port 12b, and a rear bracket 13 is provided with an intake port 13a and an exhaust port 13b. Then, the rear bracket 13 is fixed to the front bracket 12 by a fastening bolt 14, so that the stator 1 is supported between the front bracket 12 and the rear bracket 13. The rotation shaft 8 is supported via bearings 15 and 16 by the front bracket 12 and the rear bracket 13.
A pulley 17 is fixed to one end of the rotation shaft 8. A rectifier 18 is mounted on the rear bracket 13, and is electrically connected to an output terminal of the stator coil 3 so as to convert AC power generated from the stator 1 into DC power. A voltage regulator 19 is mounted to the rear bracket 13 in connection with a brush holder 20. The brush holder 20 supports a brush 21 in such a manner that this brush 21 abuts against the slip ring 9.
In the automobile AC generator constituted in the above-described manner, a current is supplied via the brush 21 and the slip ring 9 to the excitation coil 7, and at the same time, rotation torque of an engine is transported via the pulley 17 and a belt (not shown) to the rotation shaft 8, so that the rotator 4 is rotary-driven. As a result, the stator 1 may generate AC power. Then, this AC power is converted into DC power by the rectifier 18.
This automobile AC generator is mounted on the engine of the automobile for use purposes. Generally speaking, this automobile AC generator is used under very severe conditions, for instance, water, salty water, muddy water and the like are entered from the air intake holes 12a, 13a and the exhaust holes 12b, 13b into this generator. Also, this generator is exposed at high ambient temperatures. Therefore, the exposed metal portions of the structural components employed in the automobile AC generator are treated by the insulating process in order to achieve the following performance even under such severe use conditions. By this performance, the insulating characteristic of the insulated portions are not deteriorated, but also the power generation failure does not occur.
In particular, although not shown in the drawing, the rectifier 18 is constituted by the positive heat sink equipped with a plurality of positive diodes, the negative heat sink equipped with a plurality of negative diodes, and the circuit board. Thus, this rectifier 18 owns a complex three-dimensional shape. If the insulating process step is combined with the automatic assembling process step, then it is practically difficult to firmly insulating-coat the exposed surfaces of the metals such as the heat sinks, the diode connection terminals, and the voltage regulator connecting terminal while this rectifier 18 is assembled, because of such a complex shape of this rectifier 18. Therefore, conventionally, the exposed metal surfaces of the positive heat sink, the negative heat sink, and the circuit board are individually insulating-coated by the manual manner. Otherwise, the exposed metal surfaces of the positive heat sink and of the negative heat sink, to which the diodes are mounted, are manually insulating-coated under assembly condition.
As previously explained, the manual insulating coating process is carried out in the conventional rectifier used in the automobile AC generator in the following manners. That is, the exposed metal surfaces of the positive heat sink, the negative heat sink, and the circuit board are individually insulating-coated by the manual steps. Otherwise, the exposed metal surfaces of the positive heat sink and of the negative heat sink, to which the diodes are mounted, are manually insulating-coated under assembly condition. The portions other than the finally exposed portions in the conventional rectifier, namely the component mounting contact surfaces must be masked during this insulating coating process. Accordingly, there are problems that the working operations become cumbersome, and a total number of working steps is increased.
Also, in order to increase the heat radiating areas of the heat sinks, these heat sinks should have very complex concave/convex shapes. Thus, the insulating film could not be uniformly coated on the surfaces of these heat sinks. In particular, clogging, or plugging of the coating would occur among the heat radiation fins. As a result, there is another problem that the insulating films having high quality could not be formed.